71 lines
2.4 KiB
Markdown
71 lines
2.4 KiB
Markdown
---
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slug: /create-spatial-indexes
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---
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# Create a spatial index
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seekdb allows you to create a spatial index using the `SPATIAL` keyword. When creating a table, the spatial index column must be declared as `NOT NULL`. Spatial indexes can be created on stored (STORED) generated columns, but not on virtual (VIRTUAL) generated columns.
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## Constraints
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* The column definition for creating a spatial index must include the `NOT NULL` constraint.
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* The column with a spatial index must have an SRID defined. Otherwise, the spatial index on this column will not take effect during queries.
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* If you create a spatial index on a STORED generated column, you must explicitly specify the `STORED` keyword in the DDL when creating the column. If neither the `VIRTUAL` nor `STORED` keyword is specified when creating a generated column, a VIRTUAL generated column is created by default.
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* After an index is created, comparisons use the coordinate system corresponding to the SRID defined in the column. Spatial indexes store the Minimum Bounding Rectangle (MBR) of geometric objects, and the comparison method for MBRs also depends on the SRID.
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## Preparations
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Before using the GIS feature, you need to configure GIS metadata. After connecting to the server, execute the following command to import the `default_srs_data_mysql.sql` file into the database:
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```shell
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-- module specifies the module to import.
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-- infile specifies the relative path of the SQL file to import.
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ALTER SYSTEM LOAD MODULE DATA module=gis infile = 'etc/default_srs_data_mysql.sql';
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```
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<!-- For more information about the syntax, see [LOAD MODULE DATA](https://www.oceanbase.com/docs/common-oceanbase-database-cn-1000000003980607). -->
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The following result indicates that the data file was successfully imported:
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```shell
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Query OK, 0 rows affected
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```
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## Examples
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The following examples show how to create a spatial index on a regular column:
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* Using `CREATE TABLE`:
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```sql
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CREATE TABLE geom (g GEOMETRY NOT NULL SRID 4326, SPATIAL INDEX(g));
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```
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* Using `ALTER TABLE`:
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```sql
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CREATE TABLE geom (g GEOMETRY NOT NULL SRID 4326);
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ALTER TABLE geom ADD SPATIAL INDEX(g);
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```
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* Using `CREATE INDEX`:
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```sql
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CREATE TABLE geom (g GEOMETRY NOT NULL SRID 4326);
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CREATE SPATIAL INDEX g ON geom (g);
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```
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The following examples show how to drop a spatial index:
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* Using `ALTER TABLE`:
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```sql
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ALTER TABLE geom DROP INDEX g;
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```
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* Using `DROP INDEX`:
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```sql
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DROP INDEX g ON geom;
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``` |